A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?A) 6 B) 10 C) 12 D) 16 E) 18想问下答案是怎么

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A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?A) 6 B) 10 C) 12 D) 16 E) 18想问下答案是怎么

A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?A) 6 B) 10 C) 12 D) 16 E) 18想问下答案是怎么
A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?
A) 6 B) 10 C) 12 D) 16 E) 18
想问下答案是怎么算出来的,如果加减呢?我尝试用概率可是不知道怎么理解,

A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?A) 6 B) 10 C) 12 D) 16 E) 18想问下答案是怎么
中文意思是 4 红,6白,10蓝,每次随机拿一个球,问最少需要拿多少个才能确定里边含有2红、2白、2蓝.
我的思路是这样,考虑极端恶劣情况:
前10个,均为蓝.已拿10个,完成2个蓝.
再拿2个,均为白.已拿12个,完成2蓝,2白.
再拿2个,还是白.已拿14个,完成2蓝,2白.
再拿2个,还是白.已拿16个,完成2蓝,2白.
再拿2个,嗯 ,终于是红了.已拿18个,完成2蓝、2白、2红.
所以答案是E

10+6+2=18,不知道对不对啊

选18,最遭的情况是10个蓝的6个白的和2个红的都被你给拿出来了,最后才拿到第二个红的
高手啊,gre考试还有数学,英语要好到爆了才能考啊听说

A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?A) 6 B) 10 C) 12 D) 16 E) 18想问下答案是怎么 a jar was filled with gold coinsh 还是a jar fill with gold coins He has a jar in his hand.请对a jar提问. A jar contains(装有)only red,green,and blue marbles(玻璃球).If it is three times as likely(可能) that you randomly pick(随意选择) a red marble as a green marble,and five times as likely that you pick a green one as a blue one.Which of the 20mA等于多少A 请问怎么使用新class覆盖jar原class有a.jar 下面有test est.class现在我需要覆盖a.jar中的test.class, 直流电流 20uA/200uA/2mA/20mA/200mA/10A怎么念 jar是什么意思? Mobile_Token.jar 英语翻译The ability to reliably detect and track swimmers is essential for successful swimmer motion analysis.However,a swimming pool contains many motion clutters including rapid fluctuation of water surface,water ripples/reflections,etc.This ma We cover the jar with a piece of paper[改为同意句]The jar ___ ___ ___ a piece of paper 货运代理中 品名下 This shipment contains no solid wood packing ma terials 为什么要显示 This new book _____________20 articles ,_________five written by my sister.A.contains ,includes B.includes,contains c.contains,including D.includes,contained选什么,为什么? 关于contain的用法有四个句子,1.I contain several dictionary2.Sea water contains salt3.A dog contains four legs4.Mr Smith contains glasses on his nose He has a jar in his hand 改否定句,一般疑问句,肯定句,否定回答 He has a jar in his hand 否定句,一般疑问句,肯定句,否定回答 He has a jar in his hand.请改成否定句. He has a jar( in his hand).对括号里内容进行提问.